In estuarine environments where tidal forces are dominant and spring-neap tidal variations are pronounced, suspended sediment concentration (SSC) in estuarine turbidity maximum (ETM) zone does not respond instantaneously to the tidal energy (quantified by tidal range). And a phase lag is found of SSC to the tidal range. This phenomenon is confirmed by field observations at the Yalu Estuary (a macro-tidal well-mixed estuary between China and North Korea). The hysteresis in SSC during the falling and rising spring–neap cycle is traditionally interpreted by the erosion lag effects. However, here we propose another explanation with the movement of bed mud pool in estuarine turbidity maximum zone. The schematized two-dimensional depth averaged numerical models show that, during the falling and rising spring–neap cycle, the bed mud pool moves down stream and upper stream, but with pronounced delays. Because the resuspension of the bed mud pool determines the local SSC in ETM, this lag can cause the SSC delayed in response to the tidal forcing variations. The present study highlights the importance of the bed mud pool acting as a restoring force of the ETM location.